A324394 a(n) = A009194(A005940(1+n)), where A005940 is the Doudna sequence and A009194(n) = gcd(n,sigma(n)).

1, 1, 1, 1, 1, 6, 1, 1, 1, 2, 3, 4, 1, 3, 1, 1, 1, 2, 1, 2, 1, 6, 3, 12, 1, 1, 1, 1, 1, 6, 1, 1, 1, 2, 3, 28, 1, 6, 1, 10, 1, 2, 3, 12, 1, 18, 15, 4, 1, 1, 3, 1, 1, 6, 1, 3, 1, 2, 3, 4, 1, 3, 1, 1, 1, 2, 1, 4, 1, 6, 3, 8, 7, 2, 3, 28, 1, 6, 1, 2, 1, 2, 3, 28, 1, 6, 3, 120, 1, 2, 1, 6, 1, 90, 3, 12, 1, 1, 1, 7, 1, 6, 3, 5, 7, 2

Offset

0,6

Links

Antti Karttunen, Table of n, a(n) for n = 0..16384

Antti Karttunen, Data supplement: n, a(n) computed for n = 0..65537

Index entries for sequences related to binary expansion of n

Index entries for sequences related to sigma(n)

Formula

a(n) = A009194(A005940(1+n)) = gcd(A005940(1+n), A324054(n)).

Prog

(PARI) A324394(n) = { my(m1=1, m2=1, p=2, mp=p*p); while(n, if(!(n%2), p=nextprime(1+p); mp = p*p, m1 *= p; if(3==(n%4), mp *= p, m2 *= (mp-1)/(p-1))); n>>=1); gcd(m1, m2); };
(PARI)
A005940(n) = { my(p=2, t=1); n--; until(!n\=2, if((n%2), (t*=p), p=nextprime(p+1))); t }; \\ From A005940
A009194(n) = gcd(n, sigma(n));
A324394(n) = A009194(A005940(1+n));

Crossrefs

Cf. A009194, A324054, A324055, A324058, A324349, A324395.

Sequence in context: A348929 A334491 A276997 * A064793 A355925 A275109

Adjacent sequences: A324391 A324392 A324393 * A324395 A324396 A324397

Keyword

nonn

Author

Antti Karttunen, Mar 05 2019

Status

approved